The present invention relates to a new and distinct variety of sweet orange tree named ‘OLL-4’. ‘OLL-4’ is a somaclone regenerated from embryogenic callus (tissue culture) of ‘OLL’ (‘Orie Lee Late’) sweet orange, with high-quality fruit that usually matures in the standard ‘Valencia’ time period. ‘OLL’ (unpatented) is believed to be an irradiation-induced mutant line originating from ‘Pineapple’ sweet orange in an abandoned USDA trial attempting to generate a seedless ‘Pineapple’ orange. ‘OLL’ attracted attention because it never dropped fruit, a serious problem with ‘Pineapple’, and held quality late into the summer. Propagations of ‘OLL’ were not uniform and included some trees of poor growth and productivity, as well as robust high-yielding trees. In efforts to generate genetically stable clones from the ‘OLL’ selection, tissue cultures (embryogenic callus) were established for the creation of somaclones. At present, ‘OLL-4’ has been the highest yielding somaclone, and is the only remaining somaclone showing no Huanglongbing (HLB) disease symptoms. Trees of ‘OLL-4’ sweet orange topworked onto HLB-infected root/scaffold trees (‘Swingle’ and ‘Carrizo’) are also growing off quite well, but it is too early to determine the actual level of HLB tolerance. Topworked trees demonstrated true-to-typeness, as well as new trees grafted to experimental rootstocks also planted at St. Cloud, Fla.
The first asexual reproduction of the claimed tree occurred in Lake Alfred, Fla., in which original trees of ‘Hamlin’ sweet orange grafted onto ‘Carrizo’ citrange rootstock were topworked with ‘OLL-4’ in spring of 2013. Those trees produced true-to-type ‘OLL-4’ fruit.